EXTRA police officers on Chicago's streets were not enough to quell a long weekend of violence that ended with 15 people shot dead and dozens more injured.

Police Superintendent Garry McCarthy said his department's best efforts could not prevent the bloodshed that spiked dramatically on Sunday.

Chicago's total of 53 ­shooting incidents for the holiday weekend easily eclipsed Detroit and New York combined, which had a total of 46 shooting incidents, 10 of which were fatal.

"Going into the holiday weekend we had a plan, including putting hundreds more officers on the streets and what were the results?" Mr McCarthy asked.

"The results were a lot of shootings, a lot of murders, unfortunately."

The shootings over the Fourth of July holiday weekend included eight incidents that involved police, according to Mr McCarthy.

In five of those instances, officers shot at suspects. Two people - both 16 - were killed in those shoot-outs.

He said that based on preliminary investigations, all of the officer-involved shootings appear to have been justified, including one in which officers fired after a suspect tried to run them over with his car.

Mr McCarthy, who came to the third-largest US city from New York, used the opportunity to again highlight the number of guns that are on Chicago's streets and call for tougher laws.